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<head><meta charset="utf-8"><title>fuel friendly branch · wg-traits · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/index.html">wg-traits</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html">fuel friendly branch</a></h3>

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<a name="182806742"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182806742" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182806742">(Dec 06 2019 at 21:28)</a>:</h4>
<p>OK <span class="user-mention" data-user-id="232957">@Jack Huey</span> I pushed a bunch of nits and minor changes to your branch. I'm going to merge the PR, assuming travis is green. I sort of convinced myself that the strategy is correct, modulo that I think we're not handling the "refined answers" correctly, but that is probably pre-existing, as you pointed out.</p>
<p>I suspect we can continue to cleanup the code, but that seems better pursued as an iterative strategy. (If nothing else, I found that some of the comments made more sense in the recursive setup.)</p>



<a name="182806794"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182806794" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182806794">(Dec 06 2019 at 21:28)</a>:</h4>
<p>One thing I found a bit hard to read was the idiom where we would pop something from the stack after getting a result to look at the "next top-most" thing. I'm not quite sure what would make it nicer though. =)</p>



<a name="182806811"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182806811" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182806811">(Dec 06 2019 at 21:29)</a>:</h4>
<p>I think probably just a naming convention would help</p>



<a name="182806844"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182806844" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182806844">(Dec 06 2019 at 21:29)</a>:</h4>
<p>e.g., some way to flag "this is the strand that was on top from the strand we started with"</p>



<a name="182806865"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182806865" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182806865">(Dec 06 2019 at 21:29)</a>:</h4>
<p>I guess a good name might be "caller"</p>



<a name="182806872"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182806872" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182806872">(Dec 06 2019 at 21:29)</a>:</h4>
<p>maybe I'll toy with that</p>



<a name="182806978"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182806978" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182806978">(Dec 06 2019 at 21:30)</a>:</h4>
<p>I wonder also about doing something like <code>&amp;mut depth</code> for modifying the depth variable</p>



<a name="182807089"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182807089" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182807089">(Dec 06 2019 at 21:31)</a>:</h4>
<p>debatable, I guess, if the <code>depth</code> variable is even adding much value here</p>



<a name="182807111"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182807111" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182807111">(Dec 06 2019 at 21:31)</a>:</h4>
<p>oh, nm, we use it to index a lot, forgot</p>



<a name="182807512"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182807512" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182807512">(Dec 06 2019 at 21:36)</a>:</h4>
<p>Just looked through your changes, they all look good to me :)</p>



<a name="182807528"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182807528" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182807528">(Dec 06 2019 at 21:37)</a>:</h4>
<p>trying one last thing</p>



<a name="182807534"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182807534" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182807534">(Dec 06 2019 at 21:37)</a>:</h4>
<p>So, I definitely see where you're coming from with the "next top-most thing"</p>



<a name="182807618"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182807618" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182807618">(Dec 06 2019 at 21:38)</a>:</h4>
<p>I thought about this. Was thinking of how to maybe delay that handling to the beginning of the next loop (like storing some sort of answer), but didn't explore too much. If anything, it can be done iteratively</p>



<a name="182807641"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182807641" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182807641">(Dec 06 2019 at 21:38)</a>:</h4>
<p>And, honestly the depth variable is a <em>little</em> messy</p>



<a name="182807687"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182807687" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182807687">(Dec 06 2019 at 21:39)</a>:</h4>
<p>passing as <code>&amp;mut depth</code> is not the worst idea</p>



<a name="182807932"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182807932" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182807932">(Dec 06 2019 at 21:43)</a>:</h4>
<p>It might be possible to remove it though</p>



<a name="182807952"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182807952" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182807952">(Dec 06 2019 at 21:43)</a>:</h4>
<p>or at least, in most cases</p>



<a name="182808023"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182808023" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182808023">(Dec 06 2019 at 21:44)</a>:</h4>
<p>Off of the top of my head, the only place (there might be others I'm forgetting) we use it is when dealing with cycles</p>



<a name="182808596"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182808596" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182808596">(Dec 06 2019 at 21:51)</a>:</h4>
<p>OK, <span class="user-mention" data-user-id="232957">@Jack Huey</span> I have a decent commit</p>



<a name="182808654"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182808654" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182808654">(Dec 06 2019 at 21:52)</a>:</h4>
<p>it may be possible to remove depth, not sure, but this change is at least positive</p>



<a name="182808680"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182808680" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182808680">(Dec 06 2019 at 21:52)</a>:</h4>
<p>just pushed</p>



<a name="182808813"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182808813" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182808813">(Dec 06 2019 at 21:54)</a>:</h4>
<p>Ok I'll take a look</p>



<a name="182808952"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182808952" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182808952">(Dec 06 2019 at 21:56)</a>:</h4>
<p>it seems to me that there are some invariants that might be nice to document, too</p>



<a name="182808966"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182808966" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182808966">(Dec 06 2019 at 21:56)</a>:</h4>
<p>Looks good to me!</p>



<a name="182808967"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182808967" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182808967">(Dec 06 2019 at 21:56)</a>:</h4>
<p>e.g., "everything on the stack has an active strand on each turn around the loop"</p>



<a name="182808983"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182808983" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182808983">(Dec 06 2019 at 21:57)</a>:</h4>
<p>Ah true</p>



<a name="182808984"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182808984" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182808984">(Dec 06 2019 at 21:57)</a>:</h4>
<p>I suspect that's true at some point ;)</p>



<a name="182809141"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182809141" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182809141">(Dec 06 2019 at 21:58)</a>:</h4>
<p>I'm thinking about it. But we could might be able to get rid of the idea of a stack nearly entirely at some point</p>



<a name="182809198"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182809198" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182809198">(Dec 06 2019 at 21:59)</a>:</h4>
<p>I think the only thing we actually have to keep track of is the tables on the stack</p>



<a name="182812101"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182812101" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182812101">(Dec 06 2019 at 22:42)</a>:</h4>
<p><span class="user-mention" data-user-id="232957">@Jack Huey</span> Maybe. what I'm actually thinking about now is that I think the stack should <strong>persist</strong> even when we return "quantum exceeded"</p>



<a name="182812110"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182812110" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182812110">(Dec 06 2019 at 22:42)</a>:</h4>
<p>and when you enter with the same root table/index</p>



<a name="182812112"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182812112" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182812112">(Dec 06 2019 at 22:42)</a>:</h4>
<p>we should just jump back down</p>



<a name="182812115"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182812115" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182812115">(Dec 06 2019 at 22:42)</a>:</h4>
<p>without re-incrementing the clock</p>



<a name="182812125"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182812125" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182812125">(Dec 06 2019 at 22:42)</a>:</h4>
<p>otherwise, it's probably possible to have something where we don't recognize a cycle</p>



<a name="182812130"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182812130" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182812130">(Dec 06 2019 at 22:42)</a>:</h4>
<p>and besides it's kind of wasteful, no?</p>



<a name="182812136"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182812136" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182812136">(Dec 06 2019 at 22:42)</a>:</h4>
<p>but we'd have to think a bit carefully about it to make sure it all works out</p>



<a name="182812153"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182812153" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182812153">(Dec 06 2019 at 22:43)</a>:</h4>
<p>anyway, I merged the PR</p>



<a name="182812156"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182812156" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182812156">(Dec 06 2019 at 22:43)</a>:</h4>
<p>I should file some follow-up issues</p>



<a name="182813602"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182813602" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182813602">(Dec 06 2019 at 23:03)</a>:</h4>
<blockquote>
<p>and besides it's kind of wasteful, no?</p>
</blockquote>
<p>I think this is where benchmarks would be nice. Just how much overhead is there. The other thing with this: right now, when <code>QuantumExceeded</code> is returned, the next iteration pursues the <em>next</em> strand (and the current one gets put at the end)</p>



<a name="182814608"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182814608" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182814608">(Dec 06 2019 at 23:18)</a>:</h4>
<p>Well, that's by design for sure</p>



<a name="182814618"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182814618" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182814618">(Dec 06 2019 at 23:19)</a>:</h4>
<p>maybe not a good design :)</p>



<a name="182814631"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182814631" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182814631">(Dec 06 2019 at 23:19)</a>:</h4>
<blockquote>
<p>but we'd have to think a bit carefully about it to make sure it all works out</p>
</blockquote>
<p>but that is precisely the sort of interaction I was thinking about when I wrote this</p>



<a name="182814641"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182814641" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182814641">(Dec 06 2019 at 23:19)</a>:</h4>
<p>in other words: the idea of quantum exceeded was "this path isn't that great, let's try another strand"</p>



<a name="182814651"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182814651" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182814651">(Dec 06 2019 at 23:19)</a>:</h4>
<p>that said, I think there are better heuristics no doubt</p>



<a name="182814709"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182814709" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182814709">(Dec 06 2019 at 23:20)</a>:</h4>
<p>but it may be that in some cases we don't want to do that</p>



<a name="182814718"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182814718" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182814718">(Dec 06 2019 at 23:20)</a>:</h4>
<p>and I'm curious to try some other search algorithms</p>



<a name="182814754"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/fuel%20friendly%20branch/near/182814754" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/fuel.20friendly.20branch.html#182814754">(Dec 06 2019 at 23:21)</a>:</h4>
<p>Yeah, could be interesting</p>



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